Message-ID: <D9D1D797C8BE2644+74545cb0-21ea-1b04-bee1-1ed1bbe3efff@uniontech.com>
Date:   Fri, 24 Feb 2023 11:29:36 +0800
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Subject: Re: [PATCH v2] drm/vmwgfx: Work around VMW_ALLOC_DMABUF
To:     Zack Rusin <zackr@vmware.com>, "daniel@ffwll.ch" <daniel@ffwll.ch>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        Linux-graphics-maintainer <Linux-graphics-maintainer@vmware.com>,
        "airlied@gmail.com" <airlied@gmail.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <20230223070405.20228-1-tangmeng@uniontech.com>
 <c5ba07a5ad3c6b101126a97eb094c51013ee83c0.camel@vmware.com>
 <113C6E516C95FA38+f2633fe9-fb5a-616e-0e35-7559750544c9@uniontech.com>
 <2bc1750b4c3ebebf84c106b903178e5236dc396e.camel@vmware.com>
From:   Meng Tang <tangmeng@uniontech.com>
In-Reply-To: <2bc1750b4c3ebebf84c106b903178e5236dc396e.camel@vmware.com>
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On 2023/2/24 11:13, Zack Rusin wrote:
> 
> That's correct. That's the way this works. The ioctl is allocating a buffer, there's
> no infinite space for buffers on a system and, given that your app just allocates
> and never frees buffers, at some point the space will run out and the ioctl will
> return a failure.
> 
Do you mean that users without certain privileges can access allocate a 
buffer because it is designed like this? so we don't need to block 
users without certain privileges to VMW_ALLOC_DMABUF success?
> As to the stack trace, I'm not sure what kernel you were testing it on so I don't
> have access to the full log but I can't reproduce it and there was a change fixing
> exactly this (i.e. buffer failed allocation but we were still accessing it) that was
> fixed in in 6.2 in commit 1a6897921f52 ("drm/vmwgfx: Stop accessing buffer objects
> which failed init") the change was backported as well, so you should be able to
> verify on any kernel with it.
> 
> z
> 
Thank you, the kernel version of my environment is lower than 6.2, I 
will verify on my kernel with commit 1a6897921f52 ("drm/vmwgfx: Stop 
accessing buffer objects which failed init").